This invention relates to a liquid dispenser and pump for a dispenser for dispensing liquids such as soap and chemical agents and reagents.
Common liquid dispensers, such as soap dispensers found in commercial buildings and establishments, are manually operated. The user typically pulls or pushes a lever opening a passageway from the liquid reservoir. Unfortunately, liquid often flows after the lever is released not only wasting liquid but creating unsightly puddles and splashes of liquid on fixtures and cabinetry. Reservoirs can be rigid plastic bottles or collapsible bags. Rigid bottles require a vent, which may be in the form of an opening in the bottom of the bottle, so all the liquid can be removed for use. Loading bottles in the dispenser with the vent open is sometimes tricky because liquid can flow when the vent is open. Collapsible bags sometimes bind causing a malfunction and often do not empty completely not only wasting liquid but decreasing service intervals as well. It is desirable to use a rigid bottle because bottles are relatively easy to handle and empty more completely than bags, and are not as susceptible to puncture or tearing.
In some establishments lavatory water flow is controlled by a sensor that turns the water on when a hand is present under the faucet. When the hand is removed, or after a predetermined period of time, the flow stops. A motor opens and closes the valves controlling water flow. Practical motors for use with sensors do not provide the motion required to operate the levers on typical soap dispensers. Accordingly, it will be appreciated that it would be highly desirable to have a pump for a soap dispenser that uses the rotational motion of a sensor activated motor to deliver a measured amount of liquid.
In laboratory and industrial settings, chemicals and other liquids are bought and stored in large volumes because it is economical to do so on a unit basis, but they are used in very small quantities. Removing a small quantity of material from a large container exposes the bulk material to contamination and deterioration from exposure to air. Also, trying to remove a small quantity from a large container, increases the risk of spills. It is desirable to dispense a s mall a mount of material as needed without exposing the bulk material to air or increasing the risk of contamination.
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the invention, a liquid dispenser comprises a housing, an inverted bottle mounted on the housing and a cap on the bottle inside the housing. The cap defines an exit port for liquid to flow from the bottle and an entrance port for air to flow through the cap to the bottle. A screw housing is attached to the cap and defines a dispensing spout. A screw is mounted in the screw housing with the s crew transporting liquid from the cap to the dispensing when the screw rotates.
According to another aspect of the invention, a liquid dispenser comprises an inverted bottle, a cap, means for attaching the cap to the bottle, a pump disposed in the cap, and means for activating the pump. The pump includes a screw that pumps the liquid from one place to another instead of merely opening a passageway for the liquid to flow through with the assistance of gravity.
The screw has a flange on one end portion adapted to control liquid flow through the exit port by deforming when the screw rotates to allow liquid to flow out of the housing through the exit port. As liquid is carried by the screw, the liquid is pressurized sufficiently to deform the plastic flange. When the screw stops turning, the pressure is released and the flange regains its shape to block liquid flow out of the housing through the exit port.
A valve in the entrance port in the cap controls air flow through the entrance port. Air controlled by the valve replaces the dispensed liquid to equalize pressure so the liquid can flow without collapsing the bottle. The bottle is rigid to resist collapse as the liquid is pumped out of it. To prevent collapse, air is introduced into the bottle as liquid is removed via a valve which controls air flow. The screw operates for a brief period when activated to deliver a measured amount of liquid.